The present invention relates to a combinatorial weighing machine and a method of controlling the same.
Combinatorial weighing is carried out by supplying articles to weighing hoppers associated with a number of weighing machines, effecting combinatorial computations on weight values from the weighing machines, selecting an optimum weight combination having a combinatorial total weight equal or closest to a target weight value, and opening the weighing hoppers of weighing machines giving that optimum weight combination to produce a collection of articles having a total weight equal or closest to the target weight. The weighing hoppers of the weighing machines which are selected as forming the optimum weight combination and from which the articles have been discharged, are supplied with articles again, and combinatorial computations are repeated. However, with such combinatorial weighing, no combinatorial computations are performed when discharging weighed articles from the selected weighing machines and while new articles are being supplied again to the weighing machines after previous articles have been discharged, with the result that the weighing rate is low.
One combinatorial weiging process which has been proposed for increasing the weighing rate is disclosed in Japanese Laid-Open Patent Publication No. 57-86014.
According to the proposed process, about 15 weighing machines are available, and 10 or fewer weighing machines are used in each cycle of combinatorial computations. If 5 weighing machines are selected as forming an optimum weight combination, then a next cycle of combinatorial computations is effected among 10 weighing machines (the 5 weighing machines not selected as giving the optimum weight combination and the 5 weighing machines not used in the previous combinatorial compuations). During this next cycle, the articles are discharged from the 5 weighing machines selected in the present cycle and articles are thereafter supplied again to the emptied weighing machines. This process is called a parallel weighing cycle.
However, in the above process, about 5 extra weighing machines must be provided for a next combinatorial weighing cycle in addition to the 10 weighing machines which are in use for a current combinatorial weighing cycle. The disclosed process therefore requires an overall apparatus of larger size than standard apparatus with only 10 weighing machines. The large-size apparatus has a large number of parts, is costly, and requires a large installation space.